Hull construction



Nov. 25, 1952 v D, D, BRUSH 2,619,065

HULL CONSTRUCTION Filed MCh l5, 1950 IN VEN TOR.

P012 D Brush figf Patented Nov. 25, 1952 OFFICE HULL CONSTRUCTION Don D. Brush, Oregon City, Oreg., assignor of one-half to Mitchell J abczenski Application March 15, 1950, Serial No. 149,861

9 Claims.

My invention relates to hulls and, in particular, to an improved construction for a hull capable of attaining high speed.

It is of general knowledge in the hull art that greater speed may be obtained with a given structure and power plant if the friction between the hull and the water'. is reduced. One common method of reducing such friction is by pumping air along the bottom of the hull so that a thin layer of air separates the hull from contact with the water. Accordingly, many inventions have been concerned with devices for pumping or forcing air through pipes and lateral ports located along the hull bottom. Some of these inventions comprehend the use of power driven compressors to supply air to the ports. Others utilize funnels or scoops disposed along the hull sides or top to scoop in air as the hull moves at high speed over the water and to force this air out the ports along the bottom of the hull. All known devices of this character, however, require the use of either largecompressors or many feet of piping and, where no piping is utilized, the air delivery ports are located in steps built into the bottom of the hull. The disadvantage of all such structures is immediately apparent. Air scoops, compressors, and piping all add undesirable weight to the hull. Similarly, where, by example, the hull is that of a racing boat, outlet ports located in steps along the hull bottom require, by theI rules of speedboat racing, that such a boat be classified as a stepped racing boat. My invention eliminates the above enumerated disadvan tages while, at the same time, materially decreasing water friction drag on a hull and, where utilized by a speedboat, allows the speedboat employing my invention to be raced as a nonstepped boat. The advantages of my hull construction are, therefore, immediately apparent to speedboat racing enthusiasts, seaplane hull manufacturers, and ship builders.

It is a principal object of my invention to provide a hull capable of attaining high speed with air distributing slots which will circulate air over substantially the entire bottom of the hull yet which requires no expensive or burdensome extra equipment.

A more particular object of my invention is the provision of a'hull structure which will circulate air to the outlet slots without the use of air compressors or scoops.

Another object of my invention is to provide longitudinal air circulation channels between the bottom and false bottom of a hull, which channels are open at the after end or stern for the entrance of air and closed at the forward end so that air must exit through slots in the false bottom.

A further object of my invention comprehends the use of a plurality of air exit slots in the false bottom of a hull with each slot extending over the entire width of the hull bottom so that air from one slot will supplement air from another slot and substantially the entire wetted bottom of the hull will be sheathed in air at alltimes.

A more specific advantage of my invention is to be found in the fore to aft angle at which I construct my air exit slots. Such angle causes the air to leave the slots in the same direction in which the water is rushing past the bottom of the hull. This construction tends to cause the air to follow the contour of the bottom of the hull rather than to be dissipated sideways as isrthe case when the air exit angle conflicts'with the water over which a hull passes, particularly if it proceeds thereover at high speed.

These and other objects and advantages of my invention will appear from the following detailed description, taken in connection with the accompanying drawing, in which:

Fig. 1 is a side elevation of a boat having a ventilated hull embodying the features of my invention, two transverse air exit slots being shown, by way of example;

Fig. 2 is a stern view of the boat illustrated in Fig. 1 showing the air entrance channels located therein; and

Fig. 3 is a fragmentary sectional View taken along the line 3 3 in Fig. 2, showing details of an air entrance channel and air exit slots, communicating therewith.

A boat embodying my invention comprises a hull of conventional construction I, having a cockpit 2 built therein. As can be seen from Fig. 1, the bottom of the hull is shown substantially flat near the after end and is rounded or of V-shaped construction near the forward end. Such a construction is not critical, however, 'and is shown as but one example of the numerous hull constructions which can utilize my invention. The stern 3 is constructed with a proled section 4 to receive the usual outboard motor (not shown).

I prefer to construct the bottom of the hull of a boat embodying my invention of two pieces. The uppermost of these I term a bottom member 5 and the lowermost a false bottom plate 6. The bottom member 5 extends from the stern piece 3 forward to a bulkhead member I where said bottom member is secured to the top of a transverse or thwart spacer 8. The location of the bulkhead member 1 and, correspondingly, the extent to which the bottom member 5 extends in a fore-and-aft direction, is not critical.

False bottom plate 6 preferably extends from just beyond stern member 3 forward past the bulkhead I vto the bow of the boat. In this plate I form a-plurality-of'transverse air discharge slots or ports such as 9 and I6. |Ihe number of slots utilized is not critical and each given hull may employ as many or as few as best suits itsgpurposes.

Coextensive in fore-and-aft length-with the bottom member 5, I preferably place a'-plurality 1 of longitudinal spacers II to form,incooperation with said bottom member and the 'false' bottom plate 6, numerous fore and aft air circulation spaces I2. As best seen in sectional View Fig. 3,

' air"cir`culation lspaces I2 are "open at-fthe stern, as 'at `I 3, and arecl'osed :at the forward end -as bythe transverse spacer 8. Transverse slots Sand I spanmany if not allaircirculation spaces I 2 and yextendv to the underside of false bottom plate vI5. HIn addition tothe advantages previously menbottom Vmember 5 remains undamaged.

My boat, when at rest,='has its Ywaterline -substantially above Ybottom member 5. When, however, theboat travels at high velocities, Ythat is to say at velocities exceeding approximately l2 knots, thefhull exhibitsa tendency to plane somewhat and the waterline falls away accordingly. The forward motion of the boat causes a relative rearward movement of water at high velocity past air slots 9 and III. -In accordance with Bernoullis theorem, the static pressure at a given point in a flowing stream is inversely proportional to `the square of the velocity of `flow at that point, and thus a low pressure area develops along the transverse slots 9 and IB. The low pressure area thus developed causes air to ybe drawn in from the stern of the boat through openings I3, forward through air circulation spaces lI 2, and out transverse slots 9 and I0 creating, thereby, a thin separation layerk of `air between the false bottomy plemented in a fore-to-aft direction by successive elongated slots of small width. These insurefa complete separation between the wetted hull surface and the body of water over'wliich VYthe hull is propelled. v'Ihe resultant decrease in the'resistance of the water to forward movement fof the hull or in drag as it is sometimes termed produces a substantial increase in velocity avail- "able from a given propulsion horse power input.

Of particular interest are the dimensions and shape of my transverse slots 9 and IG. I have found that these slots function most efficiently when they extend over substantially the full width of the boat hull. Furthermore, as `previously noted, the *slots themselves are. preferably slanted from fore to aft as they pass through the false bottom plate in orderthat resistance to theflow of air therefrombe reduced to a' minimum. 'Since 'in accordance 4with 'my "invention,

air is drawn in from the stern by the decreased static pressure existing along the bottom of the slots, no expensive and weighty scoops, air compressors, or pipes are required to practice my invention. The ease and simplicity with which I provide a construction to completely cover the bottom of my hull with a layer of air, is an important feature of my invention.

While I have described the practice 'of my invention in connection with boat hulls, such is not to be taken as a limitation since other uses for theinvention will immediately present themselves Vto those skilled in the art. Amphibious aircraft pontoons, seaplane hulls, barges, boats, vessels, vand other 'buoyant bodies propelled over the surface of a bodyof water are all examples of such uses and therefore `within the scope of my invention. "The word hull I consider generic to all such structures.

1. A hull air channel Astructure lcomprising, coextensive bottom and false'bottomplate4 members, spacer means separating said bottom-member and said false bottom plate member to y'form longitudinal air circulation channels open 'at the after end and closed at the forward end thereof, and elongated transverse slot means .extending through said false bottom v,plate member .and connecting with at least one of saidlongitudinal airchannels, each of said air circulation .channels being closed and sealed against the Ventrance or exit of air except for said open after vend and said transverse slot means. K

2. A hull air channel structure comprisingtcoextensive bottom and lfalse bottom.` plate ,members, spacer means separating said bottom member and said false bottom plate member to v'form longitudinal air circulation-channels open atlthe after end andrclosed at the'forward endthe'reof, and elongated transverse slot meansfextending through said false bottom platejmemb'er jfor the width thereof, said openafter end andftr'ansverse slot means being the only jairentrance'jand exit openings communicating with the l:"sa'idair circulation channels. ,y

3. A hull air channel structureV comprisingQcoextensive bottom and false bottom plate members, spacer means separating said bottom member and said false bottom plate member to 'form longitudinal air circulation channels open 'at the after end and closedat the forward end thereof, and elongated transverse slot means extending through said false bottom plate member for the width thereof and slanted fore to aft from the top to the bottom thereof, each of said air ;cir culation channels being closed and sealed Iagainst the entrance or exit of lair except forksaid Aopen after end and said transverse slot means.

4. A hull air channel structure comprising, coextensive bottom and false bottom plate members, spacer means separating said bottom member-jand said false bottom plate member'and' with'said bottom member and bottom plate member defining longitudinal lair circulation channels pen at the after end and closed at theforwardnd thereof, and a plurality of velongated'trans'verse slots, arranged one behind the other from 'fore to aft, extending through said 'falsebo'ttom plate member, and connecting' with atleast one ofsaid longitudinalair channels, said open" after fend and transverseslot means fbeing thetonly'la'ir entrance and exit openings communicating with the said air irculati'on'ch'annels.

5. A hull air channelstructure comprising; cbextensive bottom and -"'fa1sefbottomi;plate niembers, spacer means separating said bottom member and said false bottom plate member and with said bottom member and bottom plate member defining longitudinal air circulation channels open at the after end and closed at the forward end thereof, and a plurality of elongated transverse slots arranged one behind the other from fore to aft and extending through said false bottom plate member for the width thereof, each of said air circulation channels being closed and sealed against the entrance or exit of air except for said open after end and said transverse slot means.

6. A hull air channel structure comprising, coextensive bottom and false bottom plate members, spacer means separating said bottom member and said false bottom plate member to form longitudinal air circulation channels open at the after end and closed at the forward end thereof, and a plurality of elongated transverse slots arranged one behind the other from fore to aft, extending through said false bottom plate member for the Width thereof, and slanted fore to aft from the top to the bottom thereof, said open after end and transverse slot means being the only air entrance and exit openings communieating with the said air circulation channels.

'7. A hull comprising a spacer structure reaching athwart, a bottom member connected fore and aft to the top of said spacer structure and to the stern respectively, a coextensive fore and aft false bottom plate connected to the bottom of said spacer structure, longitudinal means spacing said false bottom plate and said bottom member substantially the length thereof to form fore and aft air circulation spaces, and thwart air exit slots through said false bottom plate connected with at least one of said longitudinal air channels.

8. A hull comprising a spacer structure reaching athwart, a bottom member connected fore and aft to the top of said spacer structure and to the stern respectively, a coextensive fore and aft false bottom plate connected to the bottom of said spacer structure, longitudinal means spacing said false bottom plate and said bottom member substantially the length thereof to form fore and aft air circulation spaces, and thwart air exit slots through said false bottom plate the width thereof.

9. A hull comprising a spacer structure reaching athwart, a bottom member connected fore and aft to the top of said spacer structure and to the stern respectively, a coextensive fore and aft false bottom plate connected to the bottom of said spacer structure, longitudinal means spacing said false bottom plate and said bottom member substantially the length thereof to form fore and aft air circulation spaces, and thwart air exit slots through said false bottom plate the width thereof and slanted fore to aft from the top to the bottom thereof.

DON D. BRUSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 900,680 Motheral Oct. 6, 1908 1,831,697 Ziegler Nov. 10, 1931 1,894,256 De Ganahl Jan. 10, 1933 FOREIGN PATENTS Number Country Date 388,969 Germany Jan. 24, 1924 

